Parametric design of the diesel engine inlet passage
|School||Kunming University of Science and Technology|
|Course||Power Machinery and Engineering|
|Keywords||Diesel engine Helical intake port Parametric design CFD Steady flow test|
Under the premise of the same swirl intensity, helical intake port is more effective than tangential intake port and sacrifices the smallest volumetric efficiency. The spiral structure of intake port to a large extent determines the cylinder-motion of the turbulence and swirl, and therefore the performance of intake port is an important factor to affect the whole performance of the engine. However, Obtaining a intake port with satisfactory performance is a very difficult task. At present it’s also used to obtain a solid model of intake port by reverse engineering methods at home and abroad, the research on helical intake port parametric design is still more less. Based on this, the exploratory research.of helical intake port on diesel engine is carried through in this text.A new parametric design method of intake port was developed by establishing helical section curve equations and using the curve associated properties, then the helical port parametric model was founded. The numerical simulation calculation and intake port steady flow test were carried on at the same time. On the premise that the reliability of the simulative model was verified, the relation between structural parameters and performance was examined for the introduction of two performance parameters:K andθ.The variation of swirl intensity is very evident as the angle 0 value was changed; In the maximum valve lift, It can maintain the flow coefficient between 0.65-0.67, and the swirl ratio in the range of 1.6-1.8 within the scope of change.the discharge coefficient and the swirl ratio can be maintained at a relatively high level when the scale factor K is about 0.84. The variation tendency of intake port performance could be effectively controlled by adjusting the value of these two parameters.thus the quantitative relation was established between geometirc structure and the performance of intake ports. At the same time, there is always a small number of low-quality mesh as a result of automatic mesh generation technology to generate computational grid of the fluid, the above reasons, therefore the whole computational model of total inlet is divided into three sub-domain, and then arbitrary-connection technology of grid is applicated to re-form the whole computational domain, and have realized the physical continuity. Computional Grid can be found marked improvement in quality after quality inspection, thereby enhancing the process of solving the numerical stability and calculational accuracy.Parametric designing method is fundamentally superior to the traditional design method. The CAD model which constructed directly by three-dimensional modeling software has been compared with the one by gypsum or silica gel after reverse engineering. the former design process is more convenient, more obvious advantage of greatly reducing the modeling workload. Finally, the steady flow test results and simulative calculations were compared with each other.the test results show that:the calculated values matches with the experimental results much better, and have the same trend between them. Further evidence to verify the numerical simulation can effectively predict the changes of intake port performance. In various valve lift, the relative error of the discharge coefficients and swirl ratio was controlled in 12% and 15%.Of different models with distinctive helical intake port for steady flow, the trial data showed the differences in the performance of their intake port is very evident, so verify the reliability of test results on steady flow.